1. Field of the Invention
The present invention generally relates to a liquid ejection head that ejects a liquid, a method for manufacturing a liquid ejection head, and a liquid ejecting apparatus provided with a liquid ejection head. More particularly, the present invention relates to a configuration of a sealing member in a liquid ejection head in which a plurality of printing element boards are arranged linearly.
2. Description of the Related Art
A printing element board provided with a large number of printing elements, such as heating resistance elements and piezoelectric elements, is used in a liquid ejection head, such as an inkjet recording head. The greater the number of the printing elements provided in the printing element board and the longer the recording width of the printing element board, the higher the recording speed becomes. To record at a higher speed, a linear head in which a plurality of printing element boards are arranged linearly in a length corresponding to a width direction of a recording medium is receiving attention. For example, the linear head has a plurality of recording modules each having a printing element board and a support member, and a plurality of recording modules are arranged linearly in the width direction of the recording medium. PCT Japanese Translation Patent Publication No. 2010-521343 discloses a linear head in which a plurality of printing element boards are arranged linearly on a common support member. Since a common support member is used, the size of the linear head may be reduced. A plurality of printing element boards are arranged linearly in the direction parallel to the long sides. An electric wiring member for transmitting an electrical signal necessary for the ejection of a liquid to the printing element board is disposed so as to face one long side of each printing element board.
Generally, in the liquid ejection head, the printing element board and the electric wiring member are connected electrically by a conductive member, such as a wire and a lead. The conductive member is protected by a sealing member to prevent disconnection due to a short circuit caused by an ejected liquid and due to contact with the recording medium. In the liquid ejection head disclosed in PCT Japanese Translation Patent Publication No. 2010-521343, the conductive member is disposed along the long side of the printing element board. Therefore, a linear sealing member is provided continuously along the long sides of the plurality of printing element boards.
If a thermosetting sealing member is used, the liquid ejection head is heated during the manufacture to cure the sealing member. The support member, the printing element boards, and the sealing member expand when heated, are mutually fixed or restrained in a thermally expanded state. In the liquid ejection head, the coefficient of linear expansion of the sealing member is generally larger than the coefficient of linear expansion of the support member or the coefficient of linear expansion of the printing element board. Therefore, when the liquid ejection head is made to restore to a normal temperature after the sealing member is cured, the sealing member applies compressive force to the support member and the printing element boards. For this reason, the support member and the printing element boards may be bent and positions of the ejection ports on the printing element board may, therefore, be shifted, which may decrease recording quality. Further, flow paths, for example, of the printing element boards may be deformed and damaged.